Optical devices for interrogating a volume with an illumination pattern in order to obtain a mapping of the volume is known in the art per se. To achieve such an illumination pattern, it was known to use a diffractive optical element (DOE) for imparting a diffraction pattern to an incident light beam to generate the illumination pattern. However, when imparting the diffraction pattern, the DOE generally lets a zero order beam (or undiffracted beam) pass therethrough. The zero order beam can be undesired in some applications, as it can cause dynamic range issues or eye health issues, for instance.
Some optical devices for interrogating a volume with an illumination pattern include DOEs configured to provide a tiled illumination pattern by splitting and deviating the incident light beam into a plurality of adjacent diffraction patterns each having a divided zero order beam. Since each one of the partial zero order beam has a lesser power than the original zero power beam, and given their separation from one another, the optical device can be made in a manner that the zero order beam intensity is limited while retaining satisfactory power.
Still, manufacturing DOEs which can provide a tiled illumination pattern is somewhat complex since each of the diffraction pattern of the illumination pattern have to be substantially deviated one from the other in order to tile the volume with the plurality of adjacent diffraction patterns.
Although the existing techniques were satisfactory to a certain degree, there remained room for improvement, particularly in terms of reducing the complexity of manufacturing such DOEs and thus reducing the cost associated with the manufacture of such DOEs.